Sanding-machine.



PATBNTED SEPT. 4, 1906.

E. TYDEN.

SANDING MACHINE.

APPLIUATION FILED JAN.21, 1904.

5 SHEETS-SHEET l.

rn: Nokms persas ca., wAsmNcroN, n. c.

No. 830,116. PATENTED SEPT. 4, 1906. B. TYDEN.

SANDING MACHINE. APLIoATIoN H'LED @11.21. 1904 5 SHEETS-SHEET Z.

1HE Hormis Psrxns ca.. wAsHmcmN. D. c.

PATENTBD SEPT. 4, 1906.

l BTYDEN. SANDING MAGHINB. APPLIUATION PIJBDVJARRL 1904.

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,m www YN: Noll!! Plrxks C0., vlAsNlNarQN, D. c.

No. 830,116. PATBNTBD SEPT. 4, 1906.

E. TY-DEN.

SANDING MACHINE.' APPLIOATION FILED 11111.21. 1904.

5 SHEETS-SHEET 4.

60 y 60- 3 @W10 1W #wf/YX m PATENTED SEPT.4 4, 1906.

E. TYDEN.

SANDING MACHINE.

APPLIOATION FILED mum, 1904.

5 SHEETS-SHEET 5.

v ful Nokms rnfxlls cm, wAsHmoraN. m c.

IIN-ITE STATES PATENT OFFICE.

SANDlNG-NIACHINE.

Specification of Letters Patent.

Patented' sept. 4, 1906.

Application filed Ianuary 2l, 1904. Serial No 190,079.

To (LN 11171/0712/ it 77u01/ cm1/06777,:

Be it known that I, EMIL T YDEN, a citizen of the United States, residing atHastings, in the county of Barry and State of Michigan, have invented new and useful Improvements in Sanding-Machines, of which the following is a specification, reference being had to the accompanying drawings, forming a part. thereof.

The purpose of this invention is to provide an improved machine for surfacing or smoothing the surface of boards and wooden articles, particularly adapted for such use in finishing table-tops and belonging to the.

class commonly called sanding-machines.

It has, further, the specific purpose of avoiding the variations in the pressure at different parts of the work which is observable in most present machines.

It consists in the features of construction set out in the claims.`

In the drawings, Figure 1 is a front elevation with parts broken away. Fig. 2 is a plan view with the work-carriage and belts removed. Fig. 3 is a section at the line 3 3 on Fig. 1. Fig. 4 is a detail section at the line 4 4 on Fig. 1. Fig. 5 is a section at the line 5 5 on Fig. 1. Fig. 6 is a section at the line 6 6 on Fig. 5. Fig. 7 is a detail section of the valve at line 7 7 on Fig. 5. Fig. 8 is a top plan view, partly broken away to disclose the interior. Fig. 9 is a partly-sectional edge view of the pressure-bar.

This machine comprises end standards 1 and 2, rigidly joined by the base 3 and upper cross-head 4. Vertical screw-shafts 5 5, journaled in the standards, respectively, are connected within the base by an endless chain 6, passing around spiocket-wheels 7 7 on the lower ends of the shaft, respectively. These vertical screw-shafts hold and adjust the tracks for the work-carriage. These tracks 8 8 are formed as flanges upon the horizontal bars 9 9, which have lugs 10 10, projecting through vertical slots 11 in the inner sides of the standards 1 and 2, respectively, the lugs being apertured and threaded for engagement with the screw-shafts 5. For rotating the screw-shafts 5 to raise and lower the tracks, and thereby the work-carriage, one of said vertical shafts has at the upper end a beveled gear 12, which is meshed with and driven by a beveled pinion 13 on a horizontal shaft 14, journaled on the standard and adapted at its upper end to receive a key for rotating it, and thereby rotating the screw-shafts in either direction. The two bars 9 9 are rigidly connected together by cross-ties 9 9, one near eachend of the bars. The work-carriage 15 has wheels 16 16 16 16, traveling on the tracks S 8, and is provided with customary means for clamp-` ing the work, such as the jaws 17, from whose under sides lugs 18 1S project for engagement, respectively, with two right and left screw-shafts 19 19, journaled at the ends of the carriage and connected by a chain 20, passing around the sprocket-wheels 21 21 on said shafts, respectively, one or both of said shafts being adapted at one end to receive a key for rotating it, whereby the two shafts are rotated synchronously and equally for moving the jaws toward or from each other equally at both ends.

The sanding devices comprise two endless belts 22 22, passing around pulleys 23 23 and 24 24, which are journaled at the top of the standards 1 and 2 and rotated from countershafts (not shown) by belts 25 and 25a, the former passing about a pulley 26 on the shaft of one of the pulleys 23, while the other belt 25El passes around a pulley 27 on the shaftof the other pulley 23, the pulleys 24 24 being loose, one upon each of said shafts of the pulleys 23, the two pulleys 26 and 27 being roe tated in opposite directions, as indicated by the difference in the belts 25 and 25, one of which is shown as twisted and the other as straight, both being understood as driven from shafts having the same direction of ro-l tation. The lower plies of the belt-s 22 22y overhang the work-carriage, traveling in opposite directions on the work. The reason for driving the belts one from the shaft at one end of the machine and the other from the shaft at the other end is that thereby both the oppositely-travelino' operating-plies of the two belts may be actuated by pulling, as is necessary in order to prevent the liability to buckling upon encountering the frictional resistance of the work as they would do if actuated by pushing. For holding them in contact with the work they are caused to pass at their lower plies under the pressure-bar 29.

This pressure-bar is carried by the upper bar 4 of the frame. For supporting it brackets 30 30 are secured to said bar 4, having upon the upper side of said bar bearings 31 for a rock-shaft 32, which extends through all the brackets and has secured to it between the bearings of each bracket a lever-arm 33,

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projecting horizontally forward to the edge of the bracket and having pivoted to it at said forward end a suspending and guide link 34, which is vertically guided in parallel ways formed in the vertical face of the bracket. This guide-link has at the lower part and forward side a split boX 35, provided with lugs and bolt 352L and 35b for clamping it. Tn this split boX a spindle 36 is held by clamping, said spindle having pivoted to it at its lower end a flange plate or bracket 37, which is riveted or bolted to the pressure-bar for carrying the latter suspended by the link 34. For adjusting the flangeplate, and thereby the pressure-bar, transversely to level it properly to the work the spindle 36 has two lugs 38 38, projecting at opposite sides of the pivot at which it is connected to the flange-plate, and adjustingscrews 39 39, set through these lugs, impinge against the top of the flange-plate, and by causing them to protrude more or less the angle of the plate to the aXis of the spindle may be adjusted as necessary for leveling the pressure-bar. The rock-shaft 32 has made fast to it, projecting horizontally in the opposite direction from the lever-arm 33, a leverarm 40, carrying a weight 41, tending to rock the shaft in direction for lifting the pressure-bar. Another lever-arm 42, projecting from the rock-shaft at the same side as the arm 33 is connected by a link 43 with a pedal 44, fulcrumed on the base, so that the operator can apply any necessary pressure for depressing the pressure-bar against the counterweight 41 and the resistance of the work, the counterweight operating when the pedal is relieved of pressure to lift the pressure-bar from the sanding-belts and prevent them from operating on the work.

For tightening the sanding-belts there is provided at the inner side of each end standard a bracket 45, secured to the cross-head 4 and having a vertical bearing 46, in which there is vertically mounted a plunger 47, carrying in its fork 47a at the upper end a tightener-pulley 48. The plunger rests upon a spring 49, lodged in the bearing and resting in turn upon the upper end of a screw 50, which is screwed into the lower end of the bearing and provided at its protruding end with means for conveniently rotating it to tension the screw. The plunger has one side within the bearing formed with rackteeth 51, and on the bracket 45 there is mounted a spur-gear 52, meshing with the rack-teeth for raising and lowering the tightener when the gear is rotated, as may be done by means of the crank 53, applied to the protruding shaft of the gear. The detent-dog 54, pivoted on the side of the bearing 46, engages a ratchet edge 53a onthe side of the crank for locking it at a position to which it may be rotated for withdrawing the tightener-pulley from the belt.

sedile The pressure-bar 29 is formed with two longitudinal pockets 55 55 from its lower side facing the plies of the belts, respectively. In each of these pockets there are lodged short pneumatic cushions 56 in sufficient number to fill the pocket. Each cushion comprises an outer case 57 and an inner elastic tube or pouch 58 for inflation. The inner element 58 has a nipple 60, extending through the casing and through an aperture 61 in the pressure-bar, all the nipples being connected with an air-pipe 62, which leads from the source of compressed air. An inlet and vent valve 64 is interposed between each pneumatic cushion and the air-pipe 62, so that each cushion may be inflated and deflated independently of alll the others. The entire quantity of consecutive cushions in each pressure-bar channel constitute a substantially continuous air-cushion facing downward and tending to protrude from the mouth of the pocket. The pocket-mouth is, however, closed, and the pneumatic cushions are retained in said pocket by a flexible steel strap or band 65. This strap or band 65 passes around two pulleys 66 66, which are mounted upon the upper side of the pressurebar. One end of each band is made fast, and the other end is secured to one end of a spring 67, whose opposite end is connected by a swivel-eye 68 to a tension-screw 69,

-screwed through a lug 70, formed upon the upper side of the pressure-bar for that purpose, so that by means of said screw the band may be drawn taut against the under side of the cushion protruding at the mouth of the channel in the face of the pressure-bar.

It is well understood that a belt driven in the 'manner of the sanding-belts herein described for the purpose of dressing the surface of wood against which it operates tends to sag below the plane of that surface at the ICO edge at which the belt runs onto the wood. l

This results in rounding that edge, defeating the formation of an accurate corner and tending to destroy the accuracy of any corner which may have been produced by the plane or molding-machine in the previous steps of manufacture. To avoid this result, means is provided forl deflating the pneumatic cushions from the end of the pressurebar back to and including the first one inward from the 'edge of the board which is to be dressed or in some cases farther inward, so that the steel band 65 is not held down and does not hold the sanding-belt down to the surface at any point outside of or beyond that edge. This causes a slight sag Aof the belt outward from the point at-which the iirst inflated pneumatic cushion operates to give the belt a contact with the surface out to the edge,

but does not cause it to droop over the edge as IIO caused by the drag of the belt-that is, the resistance of the work to its Iprogress over itwextends the pressure sufficiently for sanding outward from the last-inated cushion suiiciently to finish the wood clear to the edge. For deflating or controlling the inflation of the pneumatic cushions, as and for the purpose above indicated, when such control is to be effected merely by adjusting the device for a particular width of board having a straight edge-that is, an edge which, as mounted in the machine, is parallel with the travel of the carriage-it is only necessary that the valves 64 of each of the cushions outward from the edge of the board at the side at which the belts respectively run onto it should be set for cutting off the supply of compressed air and venting the pneumatic. The construction of the valves in this respect is familiar, being, however, illustrated in Fig. 7, involving a vent-port 44a, which is opened by the movement of the valve which closes the inlet-port 44h. For yielding the same result when dressing boards having irregular or lateral edges which are not parallel with the travel of the carriage-as, for example, round table-to,ps -means is provided ifor automatically controlling the deflation and inflation of the pneumatic cushions by opening and closing their valves as required by the varying position of the edge in the travel of the board past the sanding-belt. This means for each of the sanding-belts consists in a shoe or slide-bar 71, which is mounted for longitudinal sliding upon the upper side of the pressure-bar immediately under the stems of the valves 64, whose operating lever-arms 64 at the open position of the valves depend in the path of said slide-bar. The bar has its forward end beveled at 71l from a point up to a maximum thickness, which is sullicient to cause it to swing the lever-arms of the valves to closed position of the valves when the bar is thrust against and on under them, lifting them from vertical toward horizontal position. rThis bar has at the outer end a depending arm 72, on which there may be mounted a roller 72a in position for bearing against the lateral edge of the work. A spring device is provided tending` to draw the bar inward, pressing the roller against the edge of the work and causing it to follow the deflections of that edge. A desirable form of such spring device consists of a drum 73, suitably mounted on the upper side of the pressure-bar, having a strap orL chain 74 secured at one end to it and rotated about it and having the other end secured to the inner end ofthe slide-bar, a helical spring 75 being secured to and coiled about the stud-axle 76, on which the drum is journaled, the outer end of the spring being attached to the drum, the spring being coiled in such direction that the outward movement of the slide-bar 7l coils the spring, rotating the drum, and the reaction of the spring tends to draw the bar inward, holding its roll against the edge of the work, as desired.

It is matter of experience and woll understood in the art that the process of dressing lumber by what is commonly called sanding-that is, rubbing it with a surface roughened by sand or other material adapted to cut the grain ,of the wood-in order to be efficient for the purpose must operate in two directions over the wood, because its movement in one direction, while cutting some protruding fibers, tends to lay the great mass of the fibers over in one direction, producing an apparently smooth surface, but one which becomes rough at once upon the application of any :finishing material-varnish, oil, or paint which moistens the fibers which have been prostrated by the one-way sanding process and causes them to erect themselves again from the surface. It is for this reason that there are provided in this machine the two oppositely-traveling sanding-belts 22 and 22. These belts, lying close together and traveling in opposite directions across the table, performing their function upon the work under the same pressure, one immediately succeeding the other, cause every portion of the work to receive exactly equal dressing in opposite directions in once traveling through the machine. Usually,

however, it is desirable to repeat the process merely for thoroughness, and the work-table is therefore caused to make a complete reciprocation, carrying the work twice under both belts and returning to the .initial position for removal of the work.

It has heretofore been customary in sanding-machines to bring the work and the sanding-belt together by advancing the former against the latter, the table or work-carrier being for that purpose arranged so as to be held upward with such force as the operator judges desirable to produce the necessary pressure and the pressure-bar back of the belt having a cushion to properly soften or distribute the pressure and yielding only for that purpose, but being otherwise in fixed position. In the construction of my machine as above described it will be noticed that the pressure is applied by the operator not through the medium of the table or work carrier, but through the medium of the cush* ioned pressure-bar, which is pressed downward to carry the belt against the work instead of having the work pressed upward against the belt. This vfeature of my con struction is of considerable importance, because when the belt is thus pressed toward the work for operating upon it it is carried outward from its normal plane of travel and trends away Vfrom the surface of the work to the drums or pulleys on which it is carried, whereas when the work is advanced against the belt the latter is thereby forced inward,

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Aand to reach the drums or pulleys it tends to making it very difficult to avoid rounding such edges and thus tending to defeat one of the purposes of its specific structure already explained in the construction of the cushion, This feature of my construction is independent 0f the plurality of the sandingbelts and is applicable equally without regard to the number or direction of travel of such sanding-belts.

1. Ina sanding-machine, in combination with two endless sanding-'belts and their driving and carrying Wheels respectively,

said belts having. their operating-surfaces forl sanding substantially parallel to the axes of their respective wheels, mechanism for rotating the wheels to drive the belts in opposite directions at their corresponding plies, and means for holding said plies to the same surface of the work.

2. In a sanding-machine, in combination with means for supporting the work, two parallel sanding-belts and their respective carrying and operating wheels means for holding corresponding operating-plies of the two belts with their surfaces which are parallel to their respective operating-shafts against the same surface of the work, and means for dri ving the shafts to propel said corresponding plies of the belts simultaneously in opposite directions.

3. In a sanding-machine, two parallel endless sanding-belts and mechanism for driving them in opposite drections; a cushion-faced pressure-bar for holding them to the work, and a longitudinally-flexible element interposed between the cushion on the one end and the oppositely-traveling belts on the other end.

4. In a sanding-machine, two parallel endless sanding-belts, and mechanism for driving them in opposite directions; a pressurebar for holding the lower ply of the belts to the work; a longitudinally-flexible element corresponding to each belt, and a cushion carried by the pressure-bar back of each such flexible element.

5. In a sanding-machine, in combination with a sanding-belt and means for driving it, a carrier for the Work opposed to the operating-ply of the belt, and means for giving it movement transverse with respect to the movement of the belt; a pressure-bar at the opposite side of said operating-ply from the work extending longitudinally with respect to the belt, and a pneumatic cushion carried in the face of the bar toward the belt for transmitting the pressure of the bar to the belt.

6. In a sanding-machine, in combination with a sanding-belt and means for driving it, a pressure-bar for holding the belt to the Work, a pneumatic cushion carried by such pressure-bar for transmitting the pressure,-

work; a cushion carried by the pressure-bar for transmitting the pressure; a longitudinally-ilexible element interposed between the cushion and the belt, and means for longitudinally straining said flexible element 8. In a sanding-machine, in combination with a sanding-belt and means for driving it, a pressure-bar for holding the belt to the work; a cushion carried by such pressure-bar for transmitting the pressure; a longitudinally-lexible element interposed between the cushion and the bottom, and a spring in the connections of such longitudinal element for yieldingly straining it longitudinally.

9. In a sanding-machine, in combination with a sanding-belt and means for driving it, a pressure-bar for holding the belt te the work; a cushion carried by the pressure-bar for transmitting the pressure; a flexible element interposed between the cushion and the belt; means about which the flexible element is deflected away from the work at the ends of the pressure-bar,- a spring connected with such flexible element beyond the guides for yieldingly straining it around the latter, and means for tensioning the spring.

l0. In a sanding-machine, in combination with a sanding-belt and means for driving it, a pressure-bar for holding the belt to the work; a cushion carried by the pressure-bar for transmitting the pressure to the belt a longitudinally-flexible element interposed between the cushion and the belt for distributing the pressure, and-means for protruding the cushion against the flexible element over a selectedpart of the latter.

1l. In a sanding-machine, in combination with a sanding-belt and means for driving it, a pressure-bar for holding the belt to the work, a cushion carried by the bar for transmitting the pressure 5 a flexible element interposed between the cushion and the belt for distributing pressure, and means for relaxing the cushions pressure against the flexible elementprogressively from the end back toward the middle of the bar.

12. In a sanding-machine, in combination with a sanding-belt and means for driving it, a pressure-bar for holding the belt to the work; a cushion carried by the bar for transmitting the pressure; a flexible element interposed between the cushion and the belt for distributing the pressure an element movable longitudinally with respect to the bar.

having an abutment bearing against the edge of the work for following the deflections of such edge, and means operated by said ele- IOO IIO

I2C A ment for relaxing the cushions pressure` progressively from the end back toward the middle of the bar.

13. In a sanding-machine, in combination with a sanding-belt and means for driving it, a pressure-bar for holding the belt to the work; a pneumatic cushion in such pressurebar comprising a multiplicity of separatelyinflated short cushions in a longitudinal series; a flexible element interposed between such pneumatic cushion and the belt, and means for controlling separately the inflation and deflation of the component short cushions.

14. In a sanding-machine, in combination with a sanding-belt and means for driving it, a pressure-bar for holding the belt to the work; a pneumatic cushion carried by the pressure-bar composed of a multiplicity of short cushions in a longitudinal series; a flexible element interposed between such pneumatic cushion and the belt; a source of compressed air for inflating the cushions, each short cushion having independent communication with such source; separate valves controlling said communications respectively, and means for operating said valves to effect the indation of said short cushions progressively from the end of the bar back toward the middle.

15. In a sanding-machine, in combination with a sanding-belt and means for driving it, a pressure-b ar for holding the belt to the work; a pneumatic cushion carried by the pressurebar consisting of a multiplicity of short cushions in a longitudinal series; a flexible element interposed between the cushions and the belt; a source of compressed air for inflating the cushions, the several short cushions having each an independent communication with such source and a valve controlling such communication; a slide-bar mounted on the pressure-bar; operating-handles for said valves, which, at corresponding` positions of the valves, stand in the path of the slideebar, and means for operating the slide-bar for encountering successively said valve-handles to operate the valves progressively from the end back toward the middle of the pressure-bar.

16. In a sanding-machine, in combination with a sanding-belt and means for driving it, a pressure-bar for holding the belt to the work; a pneumatic cushion carried by the pressure-bar consisting of a multiplicity of short cushions in a longitudinal series; a source of compressed air for inflating said cushions, each of the latter having an independent communication with said source, and a valve controlling` such communication; a slide-bar mounted on the pressure-bar having an abutment adapted to bear against the lateral edge of the work; handles for the valves respectively projecting in the path of such slide-bar for encounter thereby as the bar slides, and means for yieldingly holding the abutment to the edge of the work to cause it to follow the deflections of said edge.

17. Ina sanding-machine, in combination with a sanding-belt and means for driving it, a pressure-bar for holding the belt to the work; a pneumatic cushion carried by such pressure-bar consisting of a multiplicity of short cushions in a longitudinal series; a source of compressed air for inflating the cushions, each cushion having an independent communication with such source and a valvecontrolling such communication; a slide-bar mounted on the pressure-bar for movement longitudinally thereof; handles for the said valves projecting in the path of such movement of the bar, the bar having an abutment adapted to bear against the lateral edge of the work for following the deflections thereof; a drum mounted for rotation on the pressure-bar; a flexible connection from the periphery of the drum to the slide-bar, and a spring coiled within the drum having the inner end connected to the bearing thereof, and the outer end to the drum.

18. 1n a sanding-machine, in combination with a sandingbelt and means for driving it, a pressure-bar for holding the belt to the work; a pneumatic cushion carried by such pressure-bar consisting of a multiplicity of short cushions in a longitudinal series; a source of compressed air for inflating the cushions, each cushion having an independ ent communication with such source anda valve controlling such communication; a slide-bar mounted on the pressure-bar for movement longitudinally thereof; handles for the several valves projecting in the path of such movement of the bar, the bar having an abutment adapted to bear against the lateral edge of the work for following the deilections thereof; a drum mounted for rotation on the pressure-bar; a flexible connection from the periphery of the drum to the slide-bar, and a spring coiled within the drum having the inner end connected to the bearing thereof, and the outer end to the drum. said drum-shaft being rotatable independently of the drum and protruding from the drum and adapted to receive akeyfor rotating it, and a pawl and ratchet to retain it for tensioning the spring.

19. In a sanding-machine, in combination with two parallel sanding-belts and mechanism for driving them in opposite directions, a pressure-bar back of the operating-plies of said belts extending over the width of both of them; separate longitudinally-extending cushions carried by said bar for transmitting pressure to the two belts respectively, and separate longitudinally-flexible elements for distributing the pressure to the belts respectively.

20. In a sanding-machine, in combination IOO Vzo

with two parallel sanding-belts and mechanism for driving them in opposite directions; a pressure-b ar for holding the belts to the work separate longitudinally-extending cushions carried by the pressure-bar for transmitting pressure to the belts respectively; separate longitudinally-flexible elements interposed between the cushions and their respective belts, and separate means for protruding the cushions against their-r respectively flexible elements over selected parts of their respective lengths. l

2l. In a sanding-machine, in combination with two parallel sanding-belts and mechanism for driving them in opposite directions, a pressure-bar back of the operating-plies of said belts; separate cushions carried by the bar for transmitting the pressure to the belts respectively; separate longitudinally-flexible belts interposed between the cushions and their respective belts for distributing the pressure, and separate means for withdrawing the cushions pressure from their respective eXible elements progressively from the opposite ends back toward the middle ci the pressure-bar.

22. In a sanding-machine, in combination with two parallel sanding-belts and mechanism for driving them in opposite directions, separate pneumatic cushions carried by the pressure-bar for transmitting the pressure to the belts respectively, and separate longitudinally-leXible elements interposed between the cushions and their respective belts for distributing such pressure.

23. In a sanding-machine, in combination with two parallel sanding-belts and mechanism for driving them in opposite directions; a pressure-bar back of the operating-plies of said belts; separate pneumatic cushions carried by the pressure-b ar for the belts respectively, each of said separate cushions consisting of a multiplicity of short cushions in a longitudinal series; separate ileXible elements interposed between said cushions and their respective belts for distributing the pressure to the latter; a source of compressed air for iniiating said cushions, each of the short cushions having an independent communication with such source and a valve controlling such communication, and separate longitudinally-lexible elements interposed between the belts and their respective cushions.

24. In a sanding-machine, in combination with two parallel sanding-belts and mechan- Y ism for driving them in opposite directions, a pressure-bar back-of the operating-plies of said belts; separate pneumatic cushions carried by the pressure-bar for transmitting the pressure tothe belts respectively; separate longitudinally-flexible elements interposed between said cushions and their respective belts, each of said pneumatic cushions consisting of a multiplicity of short cushions in a longitudinal series; a source of compressed air for inflating said shortcushions, each of the latter having an independent communication with such source and a valve controlling such communication; operating connectionsior said valves and separate means for the valves oil the two series respectively mounted and movable on the pressure-bar for encountering said operating connections successively to cause the inflation or deflation of said short cushions successively along the longitudinal extent of the bar from the opposite ends. l

25. In a sanding-machine, in combination with two parallel sanding-belts and means for driving them in opposite directions, a pressure-bar back of the operating-plies of said belts; separate pneumatic cushions carried by the pressure-bar for transmitting pressure to the belts respectively; separate longitudinally-flexible elements interposed between the cushions and their respective belts, each of said cushions consisting of a multiplicity oi short cushions in a longitudinal series; a source of compressed air for ini'lating said short cushions, thelatter having independent communication with said source,

and means controlling such communication; separate elements having respectively abutments adapted to bear upon the opposite lateral edges of the work for following the delections thereof, and connections from such elements respectively for operating respectively the compressed-air communications of the short cushions of the two series progressively from the opposite ends toward the middle of the pressure-bar according to the 'degree of deiiection of said opposite edges respectively.

26. In a sanding-machine, in combination with two parallel sanding-belts having their corresponding operating-plies running side by side, edge toward edge; mechanism for IOO driving them to propel such corresponding i plies in opposite directions; means for holding the i aces of said plies which are substantially parallel with the aXes of the operatingshafts in contact with the same surface of the work; a tightener for each of the two belts and means for separately adjusting and operating such tighteners.

27. In a sanding-machine, in combination with two parallel sanding-belts having their operating-plies traveling side by side, edge toward edge, and with the surfaces of said plies which are parallel to the axes of their operating-wheels in contact with the same surface of the work; mechanism Jfor driving the belts to carry said plies in opposite directions comprising such operating-wheels; separate tighteners for the two belts; springs which hold the tighteners against their respective belts and means for separately withdrawing the tighteners against the tension of their respective springs'.

28. In a sanding-machine, in combination with a sanding-belt and mechanism for driving it, a carrier for the work opposed to the outer surface of the belt, and inea-ns for giving it movement transverse to that of the belt; a cushioned pressure-bar at the inner side of the operating-ply of the belt extending longitudinally with respect to the latter; and means for supporting' and carrying suoli pressure-bar adapted to be operated at will to press the bar outward against the operating-ply of the belt to press the latter bodily toward the work.

29. In a sanding-machine, in combination with a sandiiig-belt and mechanism for driving it, a carrier for the work adapted to hold the same opposed to the opei ating-ply of the belt; a pressure-bar at the inner side of the operating-ply of the belt; means for carrying said pressure-bar and for moving it toward and from said operating-ply, adapted to be operated at will to move the bar toward and from the belt, and a yielding take-up operating on the opposite ply of the belt.

30. In a sanding-machine, in combination with two parallel sanding-belts and mechanism for driving them in opposite directions, a carrier for the work adapted to hold the same opposed to the outer surface of the belts; a cushioned pressure-bar operating against the inner side of the operating-plies of both belts means f or suppoi'tiiig such pr essui'e-bar, and for moving it bodily toward and from the operating-plies of both belts, adapted to be operated at will for advancing said operating-plies against the work.

3l. In a sanding-inacliine, in combination with a sanding-belt and the mechanismfor driving it, a work-carrier adapted to hold the work opposed to the outer surface of the operatiiig-ply of the belt a pressure-bar and means for supporting it inovably between the two plies of the belt, and guiding it toward and from said operating-ply; a lever fulcrumed on the pressure-bar support, and connections fi'oiii such lever to the pressure-bai for moving it at will by means of the lever toward and from the operating-ply.

In a sanding-machine, in combination with the work-carrier, a frame by which it is upheld, comprising ways on which the carrier is movable to carry the work past the sanding devices,said frame comprising` a crossliead extending above the carrier in direction transverse to the ways on which the cari'ier moves; sanding-belt overhanging the workearriei', and means for driving' it in a direction transverse to said ways; a pressure-bar and supports for the same extending from said frame cross-head between the two plies of the belt, and comprising` means for guiding the pressure-bai' toward and from the operating-ply; a lever-arm fulcrumed on the crossliead, and connections therefrom to the pressure-bar for moving the pressure-bar toward and from the operating-ply.

33. In a sanding-inacliine, in combination is movable to carry the work past the sanding devices, said frame comprising' a crosshead extending above the carrier in direction transverse to the ways on which the carrier moves; a sanding-belt overhanging the workcarrier, and means for driving it in a direction transverse to said ways; a pressure-bar and suppoi'ts for the same extending from said frame cross-head between the two plies of the belt, and comprising means for guiding the pressure-bar toward and from the operating-ply a lever-arm fulcrumed on the crosshead, and connections therefrom to the pressure-bar for moving the pressure-b ar toward and from the operating-ply; a pedal at the bottom of the frame, and connection therefrom to said levers for operating the pressurebar by the foot.

34. In a sanding-macliine, in combination with the means for carrying the work, a sanding-belt and means for operating it; a pi'essure-bar back of the operating-ply of the sanding-belt, guides for the pi'essure-bar for directing its movement toward and from the belt, the pressure-bar stems which opei'ate in said guides connected to the pressure-bai' at a pivotal line extending longitudinally with respect to said bar between its latei'al edges, and adjustable stops on the guide-stems at opposite sides of said pivotal line for limiting the accomnioi'lating movement of the pressure-bar about its pivots to said stem.

35. In a sanding-machine, in combination with two parallel sanding-belts; corresponding wheels about which they are driven respectively at the two ends of their course mounted on the same shafts, said belts having their corresponding plies traveling side by side and edge toward edge with their respective surfaces which ai'e substantiallyparallel to said shafts operating for sanding in contact with the same surface of thework; mechanism for driving the two belts in opposite directions; a tightener for each of the two belts and means for separately adjusting and operating such tightcners.

36. In a sanding-machine, in combination with two parallel sanding-belts, corresponding wheels about which they are driven respectively at the two ends of their courses, said belts having their corresponding plies traveling side by side and edge toward edge, with their respective surfaces which are substantially parallel to saidshafts operating for sanding in contact with the same surface of the work, said belts having their driving'- pulleys at opposite ends of their respective courses.

37. In a sanding-niacliine, in conibination with two parallel sanding-belts, corresponding driving and idling wheels for said belts at the two ends of their respective courses, the

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ltwo driving-Wheels being at opposite ends of f said courses and means for rotating said driving-wheels in opposite directions to cause the corresponding plies of the belt to travel in opposite directions, said belts having their said corresponding plies traveling side by side and edge toward edge with their respective surfaces which are substantially parallel to said shafts operating for sanding in contact with the same surface of the work.

38, In a sanding-machine, in combination with two parallel sanding-belts, corresponding driving and idling wheels for said belts respectively, the driving-wheels for the two belts being at opposite ends of the courses of said belts and being fast on their respective shafts; means for rotating said shafts in opposite directions, the idling-wheel for each belt being loose on the shaft of the drivingwheel for the other belt.

In testimony whereof I have hereunto set my hand, in the presence of two witnesses, at Chicago, Illinois, this 15th day of December,

EMIL TYDEN. In presence of- CHAs. S. BURTON, FREDK. G. FISCHER. 

